The present invention relates to hand-held liquid dispensers. More particularly, the present invention relates to a hand-held liquid dispenser/aspirator capable of dispensing/aspirating micro-liter volumes of liquid.
In research and development settings, there are applications that require the transfer of a micro-volume amount of a single sample of reagent. Such a reagent, for example, might be withdrawn from a reservoir and delivered to a receiver, such as a well in a multi-well microtitre plate. It is usually important to perform such a transfer without cross-contamination such as may occur, for example, if a first reagent is already present in the well before a second reagent is transferred thereto.
To substantially eliminate the incidence of cross-contamination, a xe2x80x9cnon-touch-offxe2x80x9d method of fluid delivery is advantageously used. In such a method, there is no contact between a droplet being dispensed and the receiver (or fluid or other material in the receiver) until the droplet completely disengages from the tip of the dispenser. Non-touch-off transfer requires supplying kinetic energy to a droplet in an amount sufficient to overcome the surface tension of the dispensing tip and to dispense the droplet with sufficient momentum that it can be accurately and reliably directed to a desired destination.
Sophisticated table-top multi-channel dispensers have been developed for simultaneously dispensing micro volumes of liquid via non touch-off methods into a plurality of regularly spaced receivers. But relatively few xe2x80x9csingle channelxe2x80x9d (e.g., one dispensing operation at a time) hand-held dispensers are available. And those that are available are relatively simple and inaccurate xe2x80x9csyringe-xe2x80x9d or xe2x80x9cpipetter-xe2x80x9d type dispensers. Such pipetter-type dispensers are typically incapable of dispensing micro volumes of fluid.
Thus, there remains a need for an improved hand-held single channel non-touch-off dispenser.
In accordance with some embodiments of the present invention, a hand-held, single-channel dispenser is disclosed.
The present dispenser comprises a body portion for gripping the dispenser and a head portion. In some embodiments, the head portion comprises a dispensing valve, a liquid conduit and a liquid reservoir. The liquid conduit places the liquid reservoir and the dispensing valve in fluid communication. A gas conduit received by the body portion of the dispenser is operable to pressure the liquid reservoir, or draw a partial vacuum therein. Controls located on the body portion operate the dispenser.
In accordance with the illustrated embodiments of the present invention, the liquid reservoir is advantageously disposed near the dispensing valve. As a result, a relatively short length of liquid conduit is required to operatively connect the reservoir and the dispensing valve, which improves the accuracy of the dispensing operation.
In some embodiments, the liquid reservoir advantageously comprises the container portion of a standard xe2x80x9cscrew-topxe2x80x9d vial. The lid of the vial is mounted to the head portion of the dispenser. To ready the dispenser for use, the container portion is threaded into the lid. For dispensing operations, liquid is added to the container portion before it engages the lid. Alternatively, the container can be engaged to the lid empty, and, via the application of negative pressure, a liquid of choice can be aspirated into the container. Fittings are disposed through the lid so that the conduit and gas conduit can be introduced into the reservoir.
These and other features of the present invention are described in detail later in this Specification in the Detailed Description with reference to the attached Figures.